.TH std::div_sat 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::div_sat \- std::div_sat

.SH Synopsis
   Defined in header <numeric>
   template< class T >                        (since C++26)
   constexpr T div_sat( T x, T y ) noexcept;

   Computes the saturating division x / y. If T is a signed integer type, x is the
   smallest (most negative) value of T, and y == -1, returns the greatest value of T;
   otherwise, returns x / y.

   y must not be 0, otherwise the behavior is undefined. The function call is not a
   core constant expression if undefined behavior happens.

   This overload participates in overload resolution only if T is an integer type, that
   is: signed char, short, int, long, long long, an extended signed integer type, or an
   unsigned version of such types. In particular, T must not be (possibly cv-qualified)
   bool, char, wchar_t, char8_t, char16_t, and char32_t, as these types are not
   intended for arithmetic.

.SH Parameters

   x, y - integer values

.SH Return value

   Saturated x / y.

.SH Exceptions

   Throws no exceptions.

.SH Notes

   Unlike the built-in arithmetic operators on integers, the integral promotion does
   not apply to the x and y arguments.

   If two arguments of different type are passed, the call fails to compile, i.e. the
   behavior relative to template argument deduction is the same as for std::min or
   std::max.

   Most modern hardware architectures have efficient support for saturation arithmetic
   on SIMD vectors, including SSE2 for x86 and NEON for ARM.

         Feature-test macro         Value    Std          Feature
   __cpp_lib_saturation_arithmetic 202311L (C++26) Saturation arithmetic

.SH Possible implementation

   namespace detail {
   template<class T>
   concept standard_or_extended_integral =
        std::is_integral_v<T> &&
       !std::is_same_v<std::remove_cv_t<T>, bool> &&
       !std::is_same_v<std::remove_cv_t<T>, char> &&
       !std::is_same_v<std::remove_cv_t<T>, char8_t> &&
       !std::is_same_v<std::remove_cv_t<T>, char16_t> &&
       !std::is_same_v<std::remove_cv_t<T>, char32_t> &&
       !std::is_same_v<std::remove_cv_t<T>, wchar_t>;
   } // namespace detail

   template<detail::standard_or_extended_integral T>
   constexpr T div_sat( T x, T y ) noexcept
   {
       if constexpr (std::is_signed_v<T>)
           if (x == std::numeric_limits<T>::min() && y == -1)
               return std::numeric_limits<T>::max();
       return x / y;
   }

.SH Example

   Can be previewed on Compiler Explorer.


// Run this code

 #include <climits>
 #include <numeric>

 static_assert
 (""
     && (std::div_sat<int>(6, 3) == 2) // not saturated
     && (std::div_sat<int>(INT_MIN, -1) == INT_MAX) // saturated
     && (std::div_sat<unsigned>(6, 3) == 2) // not saturated
 );

 int main() {}

.SH See also

   add_sat       saturating addition operation on two integers
   (C++26)       \fI(function template)\fP
   sub_sat       saturating subtraction operation on two integers
   (C++26)       \fI(function template)\fP
   mul_sat       saturating multiplication operation on two integers
   (C++26)       \fI(function template)\fP
   saturate_cast returns an integer value clamped to the range of a another integer
   (C++26)       type
                 \fI(function template)\fP
   clamp         clamps a value between a pair of boundary values
   \fI(C++17)\fP       \fI(function template)\fP
   in_range      checks if an integer value is in the range of a given integer type
   (C++20)       \fI(function template)\fP
   min           returns the smallest finite value of the given type
   \fB[static]\fP      \fI(public static member function of std::numeric_limits<T>)\fP
   max           returns the largest finite value of the given type
   \fB[static]\fP      \fI(public static member function of std::numeric_limits<T>)\fP

.SH External links

   1.  A branch-free implementation of saturation arithmetic — Locklessinc.com, 2012
